The system development life cycle framework provides a sequence of
activities for system designers and developers to follow. It consists of
a set of steps or phases in which each phase of the SDLC uses the
results of the previous one.

The SDLC adheres to important phases that are essential for developers, such as planning, analysis, design, and implementation,
and are explained in the section below. It includes evaluation of
present system, information gathering, feasibility study and request
approval. A number of SDLC models have been created: waterfall,
fountain, spiral, build and fix, rapid prototyping, incremental, and
synchronize and stabilize. The oldest of these, and the best known, is
the waterfall model: a sequence of stages in which the output of each
stage becomes the input for the next. These stages can be characterized
and divided up in different ways, including the following:[7]

Preliminary analysis: The objective of phase 1 is to conduct a
preliminary analysis, propose alternative solutions, describe costs and
benefits and submit a preliminary plan with recommendations.

Conduct the preliminary analysis: in this step, you need to find out
the organization's objectives and the nature and scope of the problem
under study. Even if a problem refers only to a small segment of the
organization itself then you need to find out what the objectives of the
organization itself are. Then you need to see how the problem being
studied fits in with them. Propose alternative solutions: In digging into the organization's
objectives and specific problems, you may have already covered some
solutions. Alternate proposals may come from interviewing employees,
clients, suppliers, and/or consultants. You can also study what
competitors are doing. With this data, you will have three choices:
leave the system as is, improve it, or develop a new system. Describe the costs and benefits.

Integration and testing: Brings all the pieces together into a special testing environment, then checks for errors, bugs and interoperability.

Acceptance, installation, deployment: The final stage of initial development, where the software is put into production and runs actual business.

Maintenance: During the maintenance stage of the SDLC, the
system is assessed to ensure it does not become obsolete. This is also
where changes are made to initial software. It involves continuous
evaluation of the system in terms of its performance.

Evaluation: Some companies do not view this as an official
stage of the SDLC, but is it an important part of the life cycle.
Evaluation step is an extension of the Maintenance stage, and may be
referred to in some circles as Post-implementation Review. This is where
the system that was developed, as well as the entire process, is
evaluated. Some of the questions that need to be answered include: does
the newly implemented system meet the initial business requirements and
objectives? Is the system reliable and fault-tolerant? Does the system
function according to the approved functional requirements. In addition
to evaluating the software that was released, it is important to assess
the effectiveness of the development process. If there are any aspects
of the entire process, or certain stages,that management is not
satisfied with, this is the time to improve. Evaluation and assessment
is a difficult issue. However, the company must reflect on the process
and address weaknesses.

Disposal: In this phase, plans are developed for discarding
system information, hardware and software in making the transition to a
new system. The purpose here is to properly move, archive, discard or
destroy information, hardware and software that is being replaced, in a
matter that prevents any possibility of unauthorized disclosure of
sensitive data. The disposal activities ensure proper migration to a new
system. Particular emphasis is given to proper preservation and
archival of data processed by the previous system. All of this should be
done in accordance with the organization's security requirements